I think the first issue has got to be to get the lawyers off the board and get a broad range of people with aviation experience. THE AMSA board looks like a good model. An enlightened board and a diligent CEO could make a significant difference in a small number of years by simply picking off the relatively small number of recurring complaints.
The proper way to do it, is to throw it all out and start again. The vast majority of aircraft (airline & GA) are made in the US. Nearly all avioinics are made in the US. Most maintenance schedules are devised in the US. Most of aviation legislation around the world is based on the 1944 Chicago (US again) convention. It would seem to make sense to use the FAA regulations as a starting point.
20 years ago when the Victorian Gas utilities were privatised it was all done by the law firm Freehills as a outsourced deal with the Victorian Government. It was regarded as the benchmark for privatisation. We hear a lot about issues with the electricity privatisation, but I can't recall anything negative about gas.
So, the other option would be to create a couple more millionaires at law firms and outsource the whole job. It would probably be overall 1/4 the cost of having CASA in house lawyers do it and 4 times faster. The hard part for public servants is that large chunks need to be simply deleted. We are regulating things with legislation that do not need to be regulated at all.